Aim of the study: The Brief Pain Inventory is composed of two quantifiable scales: pain severity and pain interference. The reported factor structure of the interference subscale is not consistent in the extant literature, with no clear choice between a single- or two-factor structure. Here, we report on the results of Rasch-based analysis of the interference subscale using a large population-based ambulatory patient database (the Quebec Pain Registry).

Conclusion: The Interference subscale of the BPI should be interpreted as two separate subscales (Affective Interference, Physical Interference) with the sleep item removed or interpreted separately for optimal fit to the Rasch model. Implications for research and clinical use are discussed.

Aim of the study: Using the Quebec Pain Registry, (1) determine the proportion of patients referred to a multidisciplinary pain treatment facility (MPFT) at risk of opioid abuse, (2) examine biopsychosocial factors associated with this risk and (3) compare patient outcomes 6 months later across risk of opioid abuse and type of treatment (opioids vs. no opioids).

Conclusions: Almost 20% of patients had a moderate/severe risk of opioid abuse; whether these patients were taking opioids or not for their pain, they had worse outcomes at follow-up. These results point to the importance of assessing risk of opioid abuse in chronic pain patients and to consider how this risk may impact on their clinical evolution.

Aim of the study: Evaluate the validity of diagnostic codes recorded in the Régie de l'assurance maladie du Québec (RAMQ) administrative database for identifying patients suffering from various types of chronic non-cancer pain.

Conclusions: This study provides evidence supporting the value of the RAMQ administrative database for conducting research on certain types of chronic pain disorders, such as back and neck pain. However, users should be cautious with this database when studying other types of chronic pain syndromes, such as complex regional pain syndrome, fibromyalgia and neuropathic pain.

Aim of the study: Investigate the predictive association between expectations and clinical outcomes in chronic pain patients using the Quebec Pain Registry (QPR).

Conclusions: Structural equation modeling analyses showed significant positive relationships between expectations and most clinical outcomes, and this association was largely mediated by patients' global impressions of change. Similar patterns of relationships between variables were also observed in various subgroups of patients based on sex, age, pain duration, and pain classification. Such results emphasize the relevance of patient expectations as a determinant of outcomes in multimodal pain treatment programs. Further, the results suggest that superior clinical outcomes are observed in individuals who expect high positive outcomes as a result of treatment.

Aim of the study: Examine rates and correlates of unemployment across distinct common chronic pain diagnoses using the Quebec Pain Registry (QPR).

Conclusion: Depressive symptoms are associated with unemployment across a number of common chronic pain conditions, even when controlling for other factors that are associated with unemployment in these patients. Depressive symptoms, as a modifiable factor, may thus be an important target of intervention for unemployed patients with chronic pain.

Aim of the study: Assess the accuracy of self-reported prescribed analgesic medication use by comparing the data collected in the Quebec Pain Registry (QPR) database to those contained in the Quebec administrative prescription claims database (Régie de l'assurance maladie du Québec [RAMQ]).

Conclusion: Information about current prescribed analgesic medication use as reported by chronic pain patients was accurate for the main therapeutic drug classes used in chronic pain management (i.e., COX-2 selective NSAIDs, anticonvulsants, antidepressants, skeletal muscle relaxants, synthetic cannabinoids, opiate agonists / partial agonists / antagonists, and antimigraine agents). Accuracy of the past year self-reported prescribed analgesic use was somewhat lower but only for certain classes of medication, the concordance being good on all the others.

Aim of the study: Considering that pregabalin is frequently prescribed for chronic non-cancer pain, this study assessed the proportion of patients taking pregabalin for conditions approved by Health Canada ('on-label') and compare their perspectives on its use to those who use pregabalin for other conditions ('off-label').

Conclusion: Despite specific indications for pregabalin prescription, it is mainly used off-label, notably for low back pain. Nevertheless, off-label users were equally satisfied with its clinical effects. Although formal exploration of the broader analgesic properties of pregabalin is warranted, treating heterogeneous chronic pain conditions with pregabalin may be legitimate.